1. Technical Field
The present disclosure relates to an imaging apparatus, an imaging system, and an imaging method that employ a compressed sensing technique and to a recording medium.
2. Description of the Related Art
Capturing a color image requires three different pieces of wavelength information on red (R), green (G), and blue (B) corresponding to the three primary colors of light. Meanwhile, an imaging apparatus captures a color image with a single imaging device. In a conventional technique, an imaging apparatus captures a color image with a single imaging device by using a single color filter. In the present disclosure, a filter that allows visible light in a specific wavelength band to pass therethrough and blocks visible light in another specific wavelength band or a filter that allows radiation in the entire visible light wavelength band to pass therethrough is called a color filter. The aforementioned single color filter includes areas that correspond to respective pixels of the imaging device. These areas corresponding to the respective pixels each transmit light in one of red (R), green (G), and blue (B) wavelength bands. As a distribution pattern of red (R), green (G), and blue (B) in the aforementioned single color filter, a Bayer array illustrated in FIG. 20 has been widely employed. In a Bayer array, a color filter is designed such that the G pixels, which are close to the vision characteristics of human eyes, occupy one-half of all the pixels and the R pixels and the B pixels each occupy one-fourth of all the pixels. The imaging apparatus acquires wavelength information on any one of red (R), green (G), and blue (B) in each of the pixels of the imaging device by using such a single color filter. Then, a color image generating apparatus reconstructs a color image from the wavelength information received from the imaging apparatus through processing called demosaicing.
U.S. Pat. No. 5,629,734 discloses (column 2, lines 52-57) an imaging system provided with a color filter of the above-described Bayer array. The input unit of the imaging system disclosed in U.S. Pat. No. 5,629,734 can acquire only a single piece of wavelength information on red (R), green (G), or blue (B) in each of the pixels of an imaging device. Thus, a data interpolation and recording unit of the imaging system disclosed in U.S. Pat. No. 5,629,734 carries out data interpolation of the wavelength information when reconstructing a color image in a digital signal processor (column 1, lines 54-60; column 4, lines 15-33). However, information on a color that is not acquired is interpolated artificially through the data interpolation on the basis of the information on the other colors, and thus a false color can be introduced.
Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2013-511924 discloses an image processing system that includes a single color filter. In this single color filter, red (R), green (G), and blue (B) are distributed in a random pattern in areas corresponding to the respective pixels of an imaging device (paragraph 0032, paragraph 0042, FIG. 13). Therefore, only a single piece of wavelength information on red (R), green (G), or blue (B) can be acquired in each of the pixels of the imaging device. An optical converter in the image processing system disclosed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2013-511924 generates a sample data set by converting and sampling optical characteristics of an original image obtained with an image sensor (paragraphs 0027 and 0028). Then, a data processing device of the image processing system disclosed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2013-511924 reconstructs a color image by applying a compressed sensing technique to the sample data set (paragraph 0030). In Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2013-511924, as in U.S. Pat. No. 5,629,734, information on a color that has not been acquired needs to be interpolated artificially from the information on the other colors, and thus a false color can be introduced.
The above-described conventional techniques require further improvement as described above.